you know, putting your thumb between A and B and rocking back and forth is a normal thing that has existed for 30+ yearsthe only time you would want to replace A with Y would be when you're constantly pressing both A and Y at the same time, which makes sense in the NSMB seriesin smash, however, it makes less sense because I'm pretty sure you're not using A+B to do smash attacks, and instead you're using the C-stick.